Automated Measurements
SigMon users may make a variety of automated measurements, either individually or as part of an automated monitoring plan. Measurement results are stored in a database in a ring buffer configuration that keeps the latest data available. The ring buffers use a finite, configurable amount of disk space and require no maintenance to purge old data.
All measurements can be used as high performance
data loggers, recording all spectral traces, or a configured percentage of traces. Spectrum
traces are saved with date-time stamps and can be manually analyzed hours or days
after a mysterious event. SigMon can store millions
of traces. Saved traces can be played back at variable speeds in trace, waterfall
and spectrogram formats using the archived trace viewer.
Thresholds
Many measurements are made in reference to a threshold. Thresholds are displayed on the measurement trace window. A sophisticated set of automatic and fixed threshold types are supported.
Signal Logging
Signal logging is a tool that is used for automatically searching for interesting signals. Signal power and center frequency can be logged to the hard disk along with the time the signal was detected. The signal logging process can be coupled with the alarm process so that intermittent signals can be captured.
Masking
Masking, an aid to the signal logging process, can ignore signals known not to be of interest.
Carrier Measurements
Carrier measurements can be performed either manually or automatically. These measurements can also occur as the result of an alarm condition. Carrier measurements record the following parameters:
- Center Frequency
- Maximum and Average Power
- Signal-to-Noise Ratio
- Occupied Bandwidth
- Profile Compliance
- Modulation Analysis: When SigMon is configured with a DSP instrument, several parameters of a digital signal can be measured, including modulation type and symbol rate. IQ and Constellation plots can be used to examine digital signal quality.
Channel Occupancy and Statistics
The channel occupancy feature provides information on long-term usage of the spectrum. These measurements are particularly useful for allocating frequencies for best spectral economy or for verifying that reserved bands are indeed free from interference. An example of a running occupancy report is shown below.
Channelized power statistics can be used to characterize
the noise floor for channelized communications like analog cellular or TDMA and noise-sensitive
communications like CDMA. Minimum, maximum and average power can be plotted by channel
or exported to a spreadsheet with values for each user-defined time interval.
Direction Finding (DF)
Once an interesting signal or troublesome source of interference is detected and characterized, it may be useful to automatically determine the location of the transmitter. SigMon may be configured with a variety of direction finding antennas and processors, chosen to fit the frequency range of interest.